Introduction

Pathogenesis is the process by which an infection leads to disease. Pathogenic mechanisms of viral disease include implantation of virus at the portal of entry, local replication, spread to target organs (disease sites), and spread to sites of shedding of virus into the environment. Factors that affect pathogenic mechanisms are accessibility of virus to tissue, cell susceptibility to virus multiplication, and virus susceptibility to host defenses. Natural selection favors the dominance of low-virulence virus strains.

Viral pathogenesis is the study of the process and mechanisms by which viruses cause diseases in their target hosts, often at the cellular or molecular level. It is a specialized field of study in virology. Pathogenesis is a qualitative description of the process by which an initial infection causes disease. Viral disease is the sum of the effects of viral replication on the host and the host's subsequent immune response against the virus. Viruses are able to initiate infection, disperse throughout the body, and replicate due to specific virulence factors.

There are several factors that affect pathogenesis. Some of these factors include virulence characteristics of the virus that is infecting. In order to cause disease, the virus must also overcome several inhibitory effects present in the host. Some of the inhibitory effects include distance, physical barriers and host defenses. These inhibitory effects may differ among individuals due to the inhibitory effects being genetically controlled.

Other factors that determine whether infection and disease occur are the many virulence characteristics of the infecting virus. To cause disease, the infecting virus must be able to overcome the inhibitory effects of physical barriers, distance, host defenses, and differing cellular susceptibilities to infection. The inhibitory effects are genetically controlled and therefore may vary among individuals and races. Virulence characteristics enable the virus to initiate infection, spread in the body, and replicate to large enough numbers to impair the target organ. These factors include the ability to replicate under certain circumstances during inflammation, during the febrile response, in migratory cells, and in the presence of natural body inhibitors and interferon. Extremely virulent strains often occur within virus populations. Occasionally, these strains become dominant as a result of unusual selective pressures. The viral proteins and genes responsible for specific virulence functions are only just beginning to be identified.

Viral pathogenesis

Viral pathogenesis represents a complex series of interactions between viruses and the host that determine whether the virus will successfully establish infection within the host and if so, whether this infection will result in virus-induced disease. As discussed above, though the pathogenesis of each virus is unique, there are several stages in the viral life cycle that are shared by all pathogenic viruses which illustrate common themes in viral pathogenesis.

Our knowledge of viral pathogenesis is founded upon experimental data generated by many investigators over at least the last century. Much of the focus of viral pathogenesis is on viral virulence factors; however, virulence can only be defined in the context of a virus–host combination. Furthermore, there is abundant evidence that highly pathogenic viruses have been selected for specific host genetic variants within the target population.

The journal of “Medical Microbiology & Diagnosis” is a peer reviewed medical journal that includes a wide range of topics in this fields including Bacteriology, Clinical and Medical Diagnostics, Parasitology, Bacterial Infections and creates a platform for the authors to make their contribution towards the journal. The editorial office promises a thorough peer review of the submitted manuscripts to ensure quality.

Best Regards,

Mary Wilson,

Associate Managing Editor,

Medical Microbiology & Diagnosis

E-mail: microbiology@jpeerreview.com